The present invention relates to a device comprising a dispensing cap applicable to the mouth of a container of liquid or creamy substances and operable by simple rotation to close the container mouth and respectively to open it to enable said substances to be dispensed.
Various types of caps are known applicable to a container mouth to close or open passage through said mouth by merely rotating in one direction or another the most outer component forming part of the cap.
U.S. Pat. No. 4,383,623 and U.S. Pat. No. 5,810,185 describe dispensing caps formed from only two constituent parts, one superposed on and external to the other, which engage one on the other via mutually cooperating helical ribs projecting from the facing cylindrical surfaces of the two parts.
U.S. Pat. No. 3,010,619, U.S. Pat. No. 4,690,304 and U.S. Pat. No. 6,244,476 describe dispensing caps also formed from only two parts, of which the inner part is applied and retained by friction on the container mouth, while the cap outer part has a thread which engages a thread provided on the outer surface of the container mouth.
All the aforementioned dispensing caps comprise an outer component substantially in the form of a cylindrical wall with a dome at its top, in the centre of which a hole is provided through which the free end of an elongated appendix is inserted forming part of the inner cap component, to sealedly close this hole and hence prevent dispensing of the fluid substance contained in the container on which the cap is applied. The dispensing hole is opened when the cap outer component is rotated in the unscrewing direction relative to the inner component, the liquid substance then being able to be freely withdrawn from the container.
Means are provided between the cap inner component and the outer component to limit the rotation of the second relative to the first, these acting essentially as a limit stop.
Given that the cap inner component is fixed on the container mouth simply by friction, when the outer component is completely unscrewed (i.e. until it reaches the limit stop) a part of the residual torque is transmitted to the cap inner component, which can undergo stress or slight rotation about the container mouth.
This slight rotation means that the user is unable to precisely determine when the limit stop, and hence complete container opening, have been attained.
The stress subsequently transmitted to the inner body, and resulting in movement of the inner body relative to the mouth, can compromise the seal means present between these latter, hence causing undesired product leakage.